Background: CD30, a member of the tumor necrosis factor receptor superfamily, is a positive regulator of apoptosis. CD30 is expressed on activated B and T lymphocytes, Hodgkin's lymphoma R-S cells, plasma cells, NK cells, monocytes, and large lymphocytes. CD30 was expressed in classical Hodgkin's disease, anaplastic large cell lymphoma and anaplastic diffuse large B-cell lymphoma. CD30 was also expressed in primary cutaneous CD30-positive lymphoproliferative disease and some mycosis fungoides. CD30 can also be used to distinguish germ cell tumors, which are positive for embryonal carcinoma but negative for seminoma.